Method for removing deposits from hard surfaces

ABSTRACT

A method for cleaning a mirrored glass. The method includes affixing a pad to a portable, power tool; applying a composition containing an abrasive to the pad; applying the pad to the mirrored glass surface; operating the tool in a rotary motion at high speed until the mirrored glass surface is clean; and removing any excess composition from the mirrored glass surface. 
     A composition for use in cleaning mineral deposits off mirrored glass surfaces and includes a non-toxic, biodegradable solution having a pH less than 7.0 in combination with an abrasive selected from the group consisting of ground pumice stone, calcium carbonate, aluminum oxide, and diatomaceous earth. A preferred acid composition has a pH of about 4.0, and contains an abrasive with a particle size between about 3 to about 5 microns.

BACKGROUND OF THE INVENTION

This invention relates to a method for removing mineral and otherdeposits from hard surfaces such as glass, tile and the like andcompositions for such use.

In the many parts of the country, it is common to find water containingcalcium, magnesium or iron (II)ions in solution. Calcium ions derivedfrom the passage of natural waters through and over limestone are themost common metallic ions in “hard water”. Under certain conditions,insoluble salts of these metals precipitate.

Hardness in water is objectionable for several reasons. Deposits ofinsoluble metallic salts may be precipitated when water is heated orwhen soaps are added, prior to cleaning of the surface. The depositionof insoluble salts is also especially problematic when hard water comesinto contact with mirrored glass and tile surfaces. In particular,mirrored glass is used in supermarket produce cases to reflect thevegetables and to enhance the display. A misting system is commonly usedin produce cases to automatically spread water onto vegetables severaltimes each hour to help retain their freshness. Typical produce caseskeep refrigerated air constantly moving over the produce and over themirrored glass surface. The moving air causes some of the water toevaporate between the misting cycles and leads to deposition of theminerals and other foreign matter on the mirrored surface. After severalweeks this buildup is difficult to remove with conventional cleaningproducts and techniques. The buildup gives the mirror the appearance ofbeing dirty and, because of the proximity of fresh produce, it presentsan unacceptable situation with respect to the customers' perceptions ofthe store and its environs.

Various methods have been employed to prevent this problem by attemptingto remove the minerals from the water using ultrafiltration, reverseosmosis and deionization systems. These methods are only partiallysuccessful because they cannot remove all of the minerals economicallyand thoroughly. Other methods such as removing the mirrors from thesupermarket produce case entirely and cleaning them with acid has provento be costly and hazardous to the health of the personnel. Attempts toremove the deposits (i.e. scale) with steel wool typically damage theglass surface.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a simple, safe andeffective method for cleaning hard surfaces such as mirrored glass ofsupermarket produce cases, free of accumulated deposited materials.

It is a further object of the present invention to provide a method forcleaning these hard surfaces using readily available materials.

It is additional object of the present invention to provide a method ofcleaning hard surfaces which is effective in removing minerals and otherdeposits while avoiding damage to the hard surfaces themselves.

It is yet another object of the present invention to provide a safe anda effective composition for use in cleaning these hard surfaces that isnon-toxic to food produce.

A method for cleaning a mirrored glass includes affixing a pad to aportable, power tool; applying a composition containing an abrasive tothe pad; applying the pad to the mirrored glass surface; operating thetool in a rotary motion at high speed until the mirrored glass surfaceis clean; and removing any excess composition from the mirrored glasssurface. Preferably, the pad is an industrial-grade scouring pad and thecomposition is an acidic composition having a pH less than 7.0.Preferably, the power tool has a rotary motion ranging from betweenabout 9,000 to about 13,000 revolutions per minute.

A composition for use in cleaning mineral deposits off mirrored glasssurfaces comprises a non-toxic, biodegradable solution having a pH lessthan 7.0 in combination with an abrasive selected from the groupconsisting of ground pumice stone, calcium carbonate, aluminum oxide,and diatomaceous earth. Another composition for use for removingminerals from mirrored glass surfaces comprises an aqueous solution ofcitric acid, pumice powder and talc in an amount sufficient to providean abrasive composition having the consistency of putty. A preferredacid composition has a pH of about 4.0, and contains an abrasiveselected from the group consisting of ground pumice stone, calciumcarbonate, aluminum oxide, and diatomaceous earth. The most preferredabrasive has a particle size between about 3 to about 5 microns.

DETAILED DESCRIPTION OF THE INVENTION

It will be appreciated that the present method is applicable to hardsurfaces such as ceramic tile, glassed shower doors and the like.Nevertheless, the present specification will be directed to the use ofthe method and compositions to remove minerals and other deposits frommirrored glass in supermarket produce cases.

The practice of the method of this invention requires the use ofcommonly available polyester cleaning pads, in combination with commonrotary or random orbit, hand held polishing and sanding power tools. Thepreferred pads are scouring pads and are normally made from syntheticnylon or other polymer which provides a roughened surface for removingaccumulations of minerals and other deposits from hard surfaces. Thepreferred scouring pads are available in a variety of shapes andthicknesses, although white pads are preferred because they do notcontain any dye. Examples of polyester pads are “Scotch Brite” No. 9030and No. 98, manufactured by the 3M Building Surface and Cleaning ProductDivision, Saint Paul, Minn.

It may be necessary to attach the scouring pad to a backup pad and thisbackup pad may be any conventional rubber pad commonly used inconjunction with hand-held buffer/polishers or disk sanders. Preferably,the method requires the use of the scouring pads made from wovenpolyester fiber, the spaces between the fibers allowing the materialsthat are from the surface to migrate away from the work area. Thethickness of the pad is preferably about one half inch or less. Athicker pad has a tendency to shear at the center, especially when usinga random orbit power tool. Woven cloth, felt, foam rubber, and othersoft polishing materials may also be used.

Most preferably, the hand-held power tool is a random orbit tool thatwill rotate at between about 9,000 to about 13,000 rpm. Lower speeds areacceptable but will slow the removal process. The random orbit actionallows high operating speed without spraying any cleaning compositionaway from the work area. The power tool also includes a device orattachment for engaging the scouring pad. It is most preferred that partof the tool that comes in contact with the work surface comes equippedwith a Velcro®-type surface or have Velcro® attached to its surface sothat the preferred woven polyester pad will attach and hold on forsecurity. The scouring pad can also be cut to match the tool face. Otherpossible attachment methods include a drawstring apparatus, in which thescouring pad is secured to a flexible backup pad to form a scouringassembly. This particular arrangement is described in U.S. Pat. No.5,183,000.

Examples of power equipment used in the process are the Random OrbitPolisher No. 9555, manufactured by Black & Decker, Inc, Towson, Md.; aone/quarter inch drill, Model 6501 equipped with a sander head; and aRandom Orbit Sander, Model B05000, both manufactured by MakitaCorporation, Buford Ga.

In use, the scouring assembly is mounted to the portable, hand operatedpower tool and a small amount of abrasive composition of the invention,described below, is applied to the center of the scouring pad. The wholeassembly is placed on the mirrored glass. At this time, the scouring padapplied to the glass in a rotary motion imparted by the power tool. Itis important to keep the work area moist at all times, so therefore theglass must be wet or partially wet. By applying the abrasive compositionfirst to the scouring assembly and then using the rotary motion when thepad is in contact with the work surface, the abrasive composition isprevented from being thrown away from the work surface.

The tool is worked in a circular motion and if the abrasive compositionbegins to dry while being worked, more abrasive composition or liquid isadded to the surface to prevent drag on the surface which may cause heatto build up, possibly cracking or damaging the mirrored surface. It isnecessary to stop the removal process from time to time to check one'sprogress. The abrasive is periodically removed from the surface with,for example, a rubber squeegee or absorbent cloth. If more deposit needsto be removed from the surface, the above steps are repeated.

The final step in the preferred process is to protect the clean surfacewith a transparent polymer coating. Exemplary polymers are similar tothe product manufactured by Unelko Corporation, Scottsdale Ariz., underthe tradename “TPC®”. This material is a silicone polymer base thatincludes ethyl alcohol and isopropyl alcohol. This and similar productsgive the surface a thin coating which keeps the minerals from adheringto the surface, thus making regular maintenance easier because theminerals are bonded to the polymer and not to the glass.

A method of the invention for removing mineral deposits from a surfacethat has already been coated with such a protective polymer coatingincludes applying the composition of the invention directly to thescouring pad and scrubbing the surface until all of the minerals areremoved. One's progress is checked by removing the cleaning composition,as described above. Power equipment may not be needed on a surface thatis coated with transparent polymer.

Compositions of the invention for use in the above method preferablyinclude pumice-type abrasive cleaners, although commercial polishing andrubbing compounds that are used in the automotive and other industriesmay be used as well. Nevertheless, since produce and other foods come incontact with mirrors and supermarket cases, it is most preferred thatthe medium containing the abrasive be authorized by the United StatesDepartment of Agriculture for use as a general cleaning agent on allsurfaces or for use with mechanical cleaning devices. Such U.S.D.A.materials fall into category A-1.

A particularly preferred example of solution meeting this U.S.D.A.criteria are solutions made by Industrial Chemical Laboratories, Inc.,1015 North 14th Street, Omaha, Nebr., under the name of “Enviro CareFood Service Cleaner”. This material is stable, biodegradable,non-toxic, is not a fire hazard, and will not support combustion

Examples of abrasives that are most preferably used in combination withsuch a U.S.D.A. approved cleaner are ground pumice stone, iron oxide,calcium carbonate, aluminum oxide and diatomaceous earth. A wide varietyof particulate sizes can be used in suspensions of the abrasivematerials, although the most preferred size of abrasive is between aboutthree to five microns.

In addition, the preferred compositions are acidic, having a pH notgreater than 7.0, and most preferably between pH 2 to about 4. Anexemplary cleaner composition having a pH of approximately 2 includes:30 ml water; 2 ml citric acid (anhydrous, granular); 6 ml pumice powder(fine); and 30 ml talc powder. Other acids such as phosphoric and nitricacid may be used to provide the appropriate acidity but these are lesspreferred than citric acid which is milder and less toxic to theoperator and to the produce. The mixture of pumice and suspending fluidare combined together to the consistency of putty and then applied tothe scouring pad, as described above. Another exemplary formulationincludes a mixture of a one pound of pumice stone (“FF” grade;manufactured by Empie Blended Products, Inc., 250 Hickory Lane,Bayville, N.J. ) to six ounces of Enviro Care Food Service cleaner.

If necessary, immediately after the work surface has been cleaned, asolution, such as any commercially available quaternary ammoniumsolution, is applied to the work surface. Exemplary formulations of thistype may be obtained from Candy/Peck's products, 2515 West 35th Street,Chicago, Ill. 60632, under the tradename “Sanitizer”.

The method of the present invention is found to be effective in removingmineral deposits from surfaces, especially mirrored glass surfaces ofsupermarket produce cases. The present method is proven to be botheffective and to provide a distinct safety advantage by avoiding the useof cleaners harmful to foods.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described specifically herein. Suchequivalents are intended to be encompassed in the scope of the followingclaims.

What is claimed is:
 1. A method for cleaning a glass surface of amirror, comprising: affixing a pad to a portable, power tool havingmeans for engaging the pad; applying a composition having a pH less than7.0 and containing an abrasive to the pad; applying the pad to the glasssurface; operating the tool in a rotary motion at high speed until theglass surface is clean; and removing excess composition from the glasssurface.
 2. The method of claim 1, wherein affixing a pad comprisesaffixing a scouring pad.
 3. A method of claim 2, wherein affixing thescouring pad comprises affixing the pad to the power tool using a Velcroattachment.
 4. A method of claim 1, wherein the operating comprisesoperating a power tool having a rotary motion ranging from between about9,000 to about 13,000 revolutions per minute.
 5. A method of claim 1,wherein applying an acid composition comprises applying a compositionhaving a pH of about 4.0, wherein the composition contains an abrasiveselected from the group consisting of ground pumice stone, calciumcarbonate, aluminum oxide, and diatomaceous earth.
 6. The method ofclaim 5, wherein the abrasive has a particle size between about 3 toabout 5 microns.
 7. The method of claim 1, wherein applying an acidiccomposition comprises applying a composition comprising: a non-toxic,biodegradable solution having a pH less than 7 in combination with anabrasive selected from the group consisting of ground pumice stone,calcium carbonate, aluminum oxide, and diatomacious earth.
 8. The methodof claim 1 wherein applying an acidic composition comprises applying acomposition comprising an aqueous solution of citric acid, pumice powderand talc in an amount sufficient to provide an abrasive compositionhaving a consistency of putty.